Whenever this subchapter and subchapter 2 of this chapter become operative in any county or subdivision, any fence within the county or subdivision shall be deemed a lawful fence that is made of post and wire or plank, where the top wire or plank shall be five feet (5') from the ground and the wire or plank sufficiently close to keep in the class of stock embraced within this subchapter or the order of the court made in pursuance of it.